Herpes infects nerve groups, and neither your genital or oral herpes would affect your back this way. You should see a doctor to see what's going on with your back. If you had neuralgia, it would be in the sacral ganglia area (generally, the area boxer shorts would cover) or the trigeminal ganglion area (generally, the face).
Even if this was neuralgia, antivirals don't treat this. You'd need to see a neurologist for other treatment. The antivirals would help keep future obs from happening, which can help keep the nerves in check, though.
It's also very rare to get oral hsv2. Hsv2 doesn't like the mouth area, so just because you got it genitally doesn't mean you got it orally, even if you performed oral during the same encounter that you got ghsv2. If you got an oral ob shortly after your genital one, it could be the stress your body was under fighting the ghsv2 that triggered the ohsv1 outbreak.
If your general practioner won't prescribe antivirals suppressively, you can try saying you have a negative partner and you want to reduce the chances of transmission and take them daily, or find a new doctor.